The number of applications of spectrometry is constantly growing, reaching a wide range of applications like security, automotive applications, public healthcare, medical analysis and diagnosis, etc. Especially in personal healthcare, medical analysis and diagnosis, this creates a need for miniaturization and portability of spectrometers.
In the present, spectrometry is one of the easiest and least invasive techniques of analysis. A wide range of analysis is available, for instance spectroscopy based on absorption, emission, secondary emission, elastic and inelastic scattering, refraction spectroscopy, etc. Some integrated sensors based on optical characterization that can be implanted in the body of a living being have been disclosed in the past.
In order to obtain appropriate miniaturization, integrated spectrometers, that analyze the spectrum of a broadband source can be implemented on a photonic integrated circuit. Large channel count spectrometers can be realized. However, in order to obtain a fully integrated spectrometer, large detector arrays integrated with the spectrometers are required. While this is typically not an issue for applications in the visible/near-infrared, it is more cumbersome in the short-wave and mid-infrared (>1.6 um), due to the lower yield of highly sensitive, preferrably not actively cooled photodetectors in this wavelength range. It is however this wavelength range that is often of high importance for spectroscopic sensing applications. The short-wave and mid-infrared region can for example advantageously be used for spectroscopic detection of glucose or urea levels and gas compounds such as CO2, CO, NO.
In order to guarantee good performance, especially in the infrared radiation range, one typically needs to cool the detector arrays used. Cooling systems, aside of increasing the complexity and size of the device, typically consume a great amount of power. This power consumption has to be added to the power used for the transistors and components of the sensing arrays.